Fig. 7.

Revised scheme for synthesis of TMCM/TDCM and other C. glutamicum lipids. A: ketoTMCM is converted to hTMCM on the inner leaflet of the IM and subsequently acetylated (on the corynomycolic acid) or acylated (on the second glucose moiety of the trehalose headgroup), facilitating transport by the two Cmpl transporters (Cmpl1 + 4) across the IM. It is proposed that the acetyl/acyl groups are removed in the periplasm prior to the synthesis of TDCM and the transfer of MAs to the mAGP complex. The identification of Ac1-hTDCM species in this study suggests that not all of the AcTMCM is deacylated and that some of these “transport” intermediates can be converted to the Ac1-hTDCM pool. B: Several PGs, alanylated-PG, and Ala-DAG lipids were highly enriched in the IM and their levels decreased in the Δtmat mutant.